Hell Aphids
Description: take an aphid, make it about ten inches long, and give it fangs that drip foul smelling sugar. Hell Aphids have working wings, a white carapace streaked with purple and green blotches, and typically make any number of unpleasant sounds. Hell Aphids do register as faintly magical, if such spells exist in the campaign.
Hell Aphids are what happens when an evil wizard really, really hates trees and dryads. In this particular case, the wizard in question fiddled with melding aphid and demonic essences to the point where she had a murderous giant flying insect that would attack on sight the species of trees that produce dryads (as well as the dryads themselves). Hell Aphids breed true, are capable of hibernation, and their eggs can last a long time before hatching. Three can kill a dryad, and a dozen can destroy a tree in a day.
So why are there still dryads? Because the evil wizard put in a safeguard that would allow her to keep refining Hell Aphids further; the monsters are not aggressive towards anything made out of meat, even if attacked. And, since Hell Aphid flesh is so utterly unappetizing that no animal would willingly eat it, the wizard assumed that there was thus nothing standing in the way of her nefarious plan. It was frankly a horrible shock to her when the dryads promptly started hiring meat-based adventurers to kill the literally damned Aphids.
Aphid-hunting contracts are rare nowadays, but usually subject to quite competitive bidding. They offer the combination of easy work (you just have to be thorough) and good pay (Hell Aphids are scary to dryads, not to mention anybody with extensive lumber holdings). Plus, dryads and other tree spirits typically react well to an Aphid hunting team, making them useful conduits of rumors and intelligence regarding anything involving the forest.
As for the evil wizard? Well, her tower had excellent magical defenses — against wood-based attacks. She had apparently not considered the possibility that dryads might decide to hire meat-based mercenaries who would be willing to work for reasonable rates and loot. All in all, she had a real blind spot, there.
The evil wizard also didn’t for see the development of wolfpack ladybugs. Predators specialized in eating hell aphids. Normally dedicated wolfpack ladybugs are yellow with black spots running in packs of 50 to 100. With tactics similar to piranha. Most dryads now have a dedicated pack or two. When the hell aphids grew in size their greatest predator changed tactics.
Damn, now I want a ladybug wolfpack.